ARM Architecture Reference Manual ARMv7-A and ARMv7-R edition

Assembler syntax
ISB {}
where:
Instruction Details
See Standard assembler syntax fields on page A8-7. An ARM ISB instruction must be
unconditional.
Specifies an optional limitation on the ISB operation. Values are:
Operation
SY Full system ISB operation, encoded as option == '1111'. Can be omitted.
All other encodings of option are reserved. The corresponding instructions execute as full
system ISB operations, but must not be relied upon by software.
if ConditionPassed() then
EncodingSpecificOperations();
InstructionSynchronizationBarrier();
Exceptions
None.
ARM DDI 0406B Copyright © 1996-1998, 2000, 2004-2008 ARM Limited. All rights reserved. A8-103